基于微观机理的高强度钢材及其焊缝断裂预测模型研究  

Micromechanical fracture prediction model of high strength steel and its weld

作　　者：刘希月[1,2] 王元清[2] 石永久[2] 

机构地区：[1]国防科学技术大学指挥军官基础教育学院,湖南长沙410072 [2]清华大学土木工程系,北京100084

出　　处：《建筑结构学报》2016年第6期228-235,共8页Journal of Building Structures

基　　金：国家自然科学基金项目(51178244;51378289)

摘　　要：为了研究高强度钢材应用中的断裂敏感性增大和焊接连接等问题,基于材料断裂的微观机理与局部应力、应变,对Q460C高强度结构钢及其焊缝在单向拉伸作用下的断裂预测模型进行研究,分别对其母材、焊缝金属及热影响区材料进行了系列标准圆棒和缺口圆棒的单向拉伸试验,并结合有限元分析,标定材料单拉本构模型,以及细观力学模型中的材料参数。研究结果表明:Q460C焊接钢材焊缝区韧性参数大于母材和热影响区韧性参数,微孔扩张模型VGM和应力修正临界应变模型SMCS中韧性参数与钢材强度指标和屈强比没有明显关联,而与塑性指标有关,且韧性参数的离散系数在20%以内,验证了VGM和SMCS微观机理模型预测Q460C钢材及其焊缝延性断裂的有效性,为高强钢结构的断裂性能研究提供参考。The applications of high strength steel （HSS） are restricted due to the issues of brittle fracture, low ductility and welding, etc. Based on the micro fracture mechanism of high strength steel and its weld, as well as the state of local stress and strain, the micromeehanical models were proposed to predict the fracture initiation of Q460C high strength steel and the corresponding weld. Circumferentially notched round bars and smooth round bars manufactured from base metal, weld metal and HAZ were tested under monotonic tensile load. The constitutive models for 460 MPa HSS and weld materials under monotonic tensile load were established. The toughness parameters of the micromechanical models VGM and SMCS were calibrated. The results indicate that the toughness parameters are not related to the yield ratio but associated with material plasticity. This study validates the VGM and SMCS micromechanical model for HSS fracture prediction and provides basis for fracture behavior analysis on HSS structures.

关 键 词：高强度钢材 焊缝 微观机理模型 单向拉伸试验 断裂性能 

分 类 号：TU511.38[建筑科学—建筑技术科学]